This research program focuses on the biological consequences of DNA damage with the overall goal of elucidating primary events in carcinogenesis. Our goal is to elucidate molecular mechanisms by which enzymes recognize, repair, and catalyze DNA synthesis, past endogenous and exogenous damage in DNA. A principal theme of this interdisciplinary research is to establish relationships between the structure of damaged DNA and the function of enzymes involved in DNA replication and repair. Towards this end, we will use X-ray crystallography, mass spectrometry proteomics, microarray analysis, powerful new techniques that recently have emerged through structural and functional genomics research. Our specific aims are (a) to explore the role and function(s) of selected human DNA polymerases (Pol B, Pol K, and Pol in mutagenesis and DNA repair, (b) to determine the three-dimensional structures of selected DNA glycosylases bound to their cognate DNA substrates for subsequent use in elucidating the functions of amino acid residues that interact with oxidatively damaged DNA, (c) to isolate and characterize previously unidentified DNA glycosylases in eukaryotic cells, and (d) to establish the mutagenic potential of defined bistrand lesions in DNA and the molecular mechanism(s) by which such damage is repaired; in parallel, to measure global changes in gene expression induced when bistrand lesions are converted intracellularly to double-strand breaks.